Archive for the ‘black carbon’ Category

Black Carbon — New Report

March 25, 2008

A new report was published on line this weekend at Nature Geoscience:

Nature Geoscience
Published online: 23 March 2008 | doi:10.1038/ngeo156

Global and regional climate changes due to black carbon
V. Ramanathan1 & G. Carmichael2

——————————————————————————–

Abstract:

Black carbon in soot is the dominant absorber of visible solar radiation in the atmosphere. Anthropogenic sources of black carbon, although distributed globally, are most concentrated in the tropics where solar irradiance is highest. Black carbon is often transported over long distances, mixing with other aerosols along the way. The aerosol mix can form transcontinental plumes of atmospheric brown clouds, with vertical extents of 3 to 5 km. Because of the combination of high absorption, a regional distribution roughly aligned with solar irradiance, and the capacity to form widespread atmospheric brown clouds in a mixture with other aerosols, emissions of black carbon are the second strongest contribution to current global warming, after carbon dioxide emissions. In the Himalayan region, solar heating from black carbon at high elevations may be just as important as carbon dioxide in the melting of snowpacks and glaciers. The interception of solar radiation by atmospheric brown clouds leads to dimming at the Earth’s surface with important implications for the hydrological cycle, and the deposition of black carbon darkens snow and ice surfaces, which can contribute to melting, in particular of Arctic sea ice.

——————————————————————————–
The paper concluded that black carbon’s warming effect in the atmosphere is about 0.9 watts per meter squared, compared with IPCC’s consensus estimate of 0.2 to 0.4 watts.

“The positive side of this discouraging story is we know how to cut down black carbon,” Ramanathan said. “We have reduced it. So this is something we can do now.”
(Los Angeles Times, 25 March 2008 )

Advertisements